Method of manufacturing simple curvature thermoplastic composite parts

ABSTRACT

A method for manufacturing a composite part by laying up courses of composite tape using an automated tape layup (ATL) machine onto a conductive flexible facesheet laid flat on a flat surface, and then transferring the facesheet with the composite material thereon to a curved tooling surface for attachment of substructures and curing into the composite part. The method may also include applying insulation below the facesheet and above the composite material, then heating the conductive facesheet to cure the composite tape and fuse the composite tape to the substructures without heating the tooling surface or any other items used to compress and cure the composite material into the composite part. Heating of the facesheet may be performed using joule heat provided by a single turn transformer inducing current to a plurality of conductive wires attached at opposing ends to the facesheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

TECHNICAL FIELD

Embodiments of the present invention relate to methods and systems formanufacturing composite parts on a curved tooling surface.

BACKGROUND

The manufacture of structural aircraft members from layers ofthermoplastic composite materials, fiber-reinforced or otherwise, isaccomplished using a number of techniques, each having advantages anddisadvantages. Most composite aircraft structures made of unidirectionaltape are made using automated fiber placement (AFP) processes in whichindividual layers (plies) of uncured or unfused compositepre-impregnated unidirectional tape are placed on contoured tooling. AnAFP machine typically makes multiple passes or courses over the toolingto complete the placement of each layer. Each course may beapproximately eight inches wide and may consist of multiple narrowstrips of tape to better accommodate the tooling's contours. Theindividual strips making up a course must be narrow because the path ofthe tape is not always the same length across the width of the coverageof a given course. The narrow width of the individual strips of tapeapplied by AFP equipment provides a high degree of flexibility thatenables AFP layup processes to be applied to most gentle compoundcurves.

However, programming and manipulating an AFP head to follow contoursreduces the speed that an AFP machine can move. Furthermore, the narrowstrips of material required for AFP processes are expensive because eachstrip must be separately slit, inspected, and packaged. Additionally,AFP machines are often mechanically complex and costly because they mustbe designed to feed and apply up to 16 separate strips of materialsimultaneously. Therefore, automated tape laying (ATL) processes aretypically used for large, flat parts rather than AFP processes. WithATL, courses of full width tape are applied rather than courses composedof multiple narrow strips. An ATL course may also be wider than an AFPcourse. Thus, ATL is more efficient than AFP, since the tape's widerwidth allows the tape-laying machine to cover the same tooling area infewer passes. ATL also uses less expensive materials than AFP. However,ATL tape cannot be applied using differential speeds from one side of acourse to the other, and rollers of ATL machines are typically wider,more solid than, and generally not as compliant as rollers for AFPmachines. Due to these limitations, ATL is generally not compatible withcurved contours and is largely relegated for use in making flat ornearly flat composite components. There are many parts having only asimple curvature where the level of flexibility provided by AFP isunnecessary, and where AFP is more costly and inefficient than desired,but where traditional ATL processes are not compatible with thecurvature of the part mold or tooling.

Another problem in the manufacturing of composite parts, particularlythose with some type of curvature, occurs due to thermal expansion.Specifically, once tape laying or composite fiber placement is complete,the composite tape is cured (thermoset) or fused (thermoplastic). Thiscuring or fusing process may involve the composite tape layers beingcompressed via vacuum and autoclave pressure and heated past theirmelting or curing point, consolidating the layers of composite tapetogether. Once the pressure and heat are removed, the consolidatedcomposite material becomes a hardened composite part having the shape ofthe mold or tooling on which it was cured or fused. However, the mold ortooling on which the composite part is cured or fused generallyexperiences some thermal expansion during curing or fusing of thecomposite part. Thus, in order to ensure that the thermal expansion doesnot result in an incorrectly sized composite part, the mold or toolingmust be carefully sized with this thermal expansion factored in. Evensmall sizing errors or changes in an amount of heat applied may resultin an incorrectly sized composite part. Furthermore, incorrect sizingcan in some situations even lead to the mold or tooling breaking thecomposite part if both cool and shrink at different rates, particularlyfor curved composite parts. Note that heating an entire oven orautoclave, as well as heating the mold or tooling and the composite partalso requires a large amount of power.

Yet another difficulty in composite part manufacture, particularly foraircraft structures, is combining composite parts together after theyare individually cured or fused. For example, a composite componentreferred to as “skin” is often joined together with substructures suchas frames and stringers serving as an internal frame for the compositepart. This may be done by means of fasteners, but it generally moredesirable to integrate the parts as a single monolithic structure.Co-curing, co-molding or fusing of the skin with the substructures isone method of joining these components without adding holes andfasteners which can increase the overall weight and cost of the aircraftstructure. In co-curing, co-molding, or fusing together of two compositecomponents, the substructures may be placed against the skin and thecombination may be placed in an oven or autoclave for application ofheat and fusing of the substructure to the skin. Traditional approachesfor co-curing, co-molding, or fusing composite components in this mannermay include multiple complex tooling or mold components to providesufficient pressure for maintaining the shape and consolidation of thepreviously-formed composite components as they are cured together orre-melted to fuse them. Thus, such co-curing or fusing lay-up techniquescan be complicated and time-consuming.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential elements of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter. The present invention is defined by the claims.

At a high level, aspects herein relate to placing layers of compositematerial courses, also referred to as composite tape, onto a facesheeton a flat surface and then transferring the facesheet and compositematerial onto a curved tooling surface for curing, melting, or fusing ofthe composite material thereon into a composite part. Specifically,various embodiments of the invention may include placing or forming askin made of a plurality of layers of uncured or unfused compositematerial onto a facesheet made of a flexible thermally and/orelectrically conductive material. Next, the facesheet with the skinthereon may be transferred onto a tooling surface made of insulatingmaterial or having a first insulating material positioned thereonbetween the tooling surface and the facesheet. Then the facesheet may beplaced in electrical and/or physical contact with a source of heat orelectricity and a second insulating skin may be placed over the skin.Furthermore, a substantially impermeable membrane may be placed over thesecond insulating material and the skin, sealed to the tooling surface,and forced via a pressure differential toward the tooling surface,thereby compressing the skin. Next, the facesheet may be heated to aprocessing temperature for curing, melting, and/or fusing the skin andthen the skin is cooled and/or hardened.

Various embodiments of the invention may also include forming the skinusing an automated tape laying (ATL) machine for laying courses ofcomposite material onto the facesheet on a flat surface in accordancewith ATL methods known in the art. Furthermore, the tooling surface ontowhich the facesheet and skin are transferred may be curved. In someembodiments, heating the facesheet to the cure temperature, meltingtemperature, and/or fusing temperature of the skin is performed viajoule heating. Specifically, the facesheet may be heated using a singleturn transformer inducing current into a plurality of conductive wiresextending from one end of the skin to an opposite end of the skin andthreaded through an air gap of the single turn transformer.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present invention will be apparent from thefollowing Detailed Description and the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples are described in detail below with reference to the attacheddrawing figures, wherein:

FIG. 1 is a perspective view of an automated tape layup (ATL) machinelaying composite tape onto a flat surface to form a composite skin inaccordance with embodiments of the present invention;

FIG. 2 is a perspective view of a portion of the ATL machine with amagnet placement apparatus attached therein in accordance with anembodiment of the present invention;

FIG. 3 is a perspective view of a curved tooling surface with a firstinsulating material laid thereon in accordance with an embodiment of thepresent invention;

FIG. 4 is a perspective view of the tooling surface of FIG. 3 with thecomposite skin of FIG. 1 being placed thereon;

FIG. 5a is a side elevation cross-sectional view of the tooling surfaceof FIG. 4 taken along line 5-5 in FIG. 4, further depicting the firstinsulating material, the facesheet, the composite skin, substructures, asecond insulating material, and an impermeable membrane layered thereonfor curing in an autoclave in accordance with embodiments of the presentinvention;

FIG. 5b is a front elevation view of a single turn transformer of FIG.5a ;

FIG. 6 is a fragmentary side elevation view depicting a close-up oflayers of materials depicted in FIG. 5; and

FIG. 7 is an exemplary method of forming and curing a composite part inaccordance with embodiments of the present invention.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which thetechnology herein can be practiced. The embodiments are intended todescribe aspects of the invention in sufficient detail to enable thoseskilled in the art to practice the invention. Other embodiments can beutilized and changes can be made without departing from the scope of thepresent invention. The following detailed description is, therefore, notto be taken in a limiting sense. The scope of the present invention isdefined only by the appended claims, along with the full scope ofequivalents to which such claims are entitled.

As depicted in FIGS. 1-6, aspects herein relate to a system 10 andmethod of forming a thermoplastic composite part. In some aspects, asdepicted in FIGS. 1-2, the system 10 comprises a facesheet 12 and anautomated tape layup (ATL) machine 14 for laying courses of compositematerial, referred to herein as composite tape 16, onto a flat surface18. The system 10 may also include a magnet placement apparatus 20 fordispensing and collecting magnets 22 for holding down the composite tape16 during various stages of ATL on the flat surface 18. Furthermore, thesystem 10 may comprise a tooling surface 24, a first insulating material26, a second insulating material 28, and a source of heat or electricity30. In some embodiments, the system 10, as depicted in FIGS. 5a and 6,may include an impermeable membrane 32 for placement over the secondinsulating material 28 and the thermoplastic composite part forproviding compressive force to the composite tape 16 and/or otherportions of the composite part during curing thereof.

The composite part being manufactured by the system 10 and method hereinmay be made from thermoset or thermoplastic composite material and mayinclude a composite skin 34 co-cured or fused to at least one compositesubstructure 36, as depicted in FIGS. 5a and 6. Specifically, thecomposite skin 34 may be for aircraft components such as a fuselage orengine nacelle, and the substructure 36 fused thereto may be one or moreframes and/or stringers providing structural reinforcement to thecomposite skin 34. The composite skin 34 can be formed using a pluralityof layers of composite plies and/or composite tape 16. The compositetape 16 or plies may be made of carbon-fiber reinforced epoxy and mayspecifically be a prepregged unidirectional tape or continuous strip offabric. For example, composite tape 16 used for ATL methods describedherein may be approximately twelve inches in width and may be of a formapproximately 40% less expensive than an equivalent amount of eight-inchtape widths (e.g., slit tape) traditionally used for automated fiberplacement (AFP) methods. The substructure 16 may include frames,stringers, or other composite part structures for being fused orotherwise integrated with another composite part or composite skin 34.

The facesheet 12 may be made of a thin, flexible conductive materialhaving high resistivity such as steel (e.g., 304 Stainless Steel, A36Steel, or the like). Note that although the steel itself may besubstantially rigid, the facesheet may be thin enough that the steel mayflex sufficiently for conforming to simple curvatures, as laterdescribed herein. However other conductive materials may be used withoutdeparting from the scope of the technology described herein. In someembodiments, facesheet 12 may have a thickness sufficient to support thecomposite tape 16 thereon, such as a thickness in a range of 0.01 inchesto 0.1 inches. For example, the thickness may be approximately 0.032inches for providing an optimum flexibility and sufficient resistance toenable four or more volts of potential.

The ATL machine 14 is configured for laying courses of compositematerial (e.g., composite tape 16) onto the facesheet 12 on the flatsurface 18 prior to insertion of the facesheet 12 onto the toolingsurface 24, as later described herein. For example, the ATL machine 14may include a robotically controlled head 38, as depicted in FIG. 2,including a spool or spools of composite tape, a winder, winder guides,a compaction shoe, a position sensor, and/or a tape cutter or slitter.However, other ATL machine configurations known in the art may be usedfor ATL composite tape layup without departing from the scope of thetechnology described herein. The ATL machine 14 lays down the compositetape 16 at various desired path orientations which may vary betweendifferent layers of the composite skin 34. To hold the courses ofcomposite material down in their desired orientations prior to curing orfusing, various types of welding or tacking are traditionally used(e.g., heating and adhering each strip to previously deposited layers asit is applied) but may not be preferred in some embodiments of theinvention described herein because such traditional means of tacking mayrender a stack of composite layers unable to conform along with thefacesheet 12 without wrinkling when it is transferred from the flatsurface 18 to the tooling surface 24 as described below. Thus,strategically placed localized tacking and/or removable magnets 22 aredescribed herein to replace such traditional welding or tacking methodsfor ATL. In some embodiments, each layer of composite material may beadhered to the previously applied layer in only certain locations (e.g.,at locations along a center line in a direction of bend for thecomposite skin 34). If some layers of composite material do not coverthe entire area of the facesheet 12 (e.g., doubler plies), such layersmay be tacked at a centerline in a direction of bend of such layer whichcenterline may not coincide with the centerline of the overall compositeskin 34. The locations at which each layer of composite material isadhered to the underlying layer may be determined strategically tominimize wrinkling when the facesheet 12 is transferred from the flatsurface 18 to the tooling surface 24 as described below. The layers maybe adhered at strategic locations by welding (e.g., ultrasonic welding,conduction welding, etc.) or by selective heating of courses ofcomposite material during initial application to cause adhesion at onlycertain locations. Alternatively, in some embodiments, the layers may betacked, adhered, or held together over substantially the entire area ofthe skin 34, but in a manner that allows some inter-layer movement tooccur during the transfer of the facesheet 12 from the flat surface 18to the tooling surface 24 as described below. For example, each layermay be welded to the underlying layer at locations so small that theresin joining the two layers can shear if relative movement is requiredbetween layers. Alternatively, magnets may be used to compress thelayers together and create friction therebetween, thus holding thelayers in position while allowing them to slide if required during thetransfer of the facesheet 12 from the flat surface 18 to the toolingsurface 24 as described below.

Specifically, the magnetic placement apparatus 20 is a device operableto lay down and pick up magnets 22 by effectuating a change in polarityof portions of the magnetic placement apparatus 20. The magnets 22 maybe rare earth magnets such as neodymium magnets attracted to thefacesheet 12. For example, the magnet placement apparatus 20 may beconfigured to place the magnets 22 onto a first layer of courses ofcomposite material during layup by the ATL machine 24 and to pick upmagnets 22 from the courses of composite material prior to the ATLmachine 14 placing a second layer of courses of composite material(e.g., composite tape 16). In some embodiments, the magnets 22 are justapplied at a center line in a direction of bend for the composite skin34, as depicted in FIG. 4. Furthermore, in some embodiments, the magnetplacement apparatus 20 may be a rotatable steel ring around atape-laying head of the ATL machine 14, as depicted in FIGS. 1-2, andthe ring may rotate to move the magnets 22 from in front of the ATLmachine tape-laying head to behind the tape-laying head where themagnets 22 are then replaced on a latest or last layer of the compositetape 16.

In some embodiments, the tooling surface 24 is made of insulatingmaterial or alternatively the first insulating material 26 is positionedonto the tooling surface 24, as depicted in FIG. 4. At least a portionof the tooling surface 24 is not flat. For example, the tooling surface24 may have a simple curvature for forming a curved composite part suchas an outer mold line (OML) or outer surface of the skin 34 for aircraftcomponents such as a fuselage or engine nacelle. Additionally oralternatively, the tooling surface 24 may have other curvatures. Thetooling surface 24 may be formed from any material without departingfrom the scope of the technology described herein. In some embodiments,any structural frame or base may support the tooling surface in adesired curvature.

The size and shape of the tooling surface 24 may correspond with thecomposite part to be formed thereon. For example, the composite part maybe formed on the tooling surface 24 to have three-dimensionalcharacteristics such as height, depth, curvature, contours, featuresthat intersect at angles up to and including ninety degrees, or featuresthat include a space between them. In some embodiments, the size of thetooling surface 24 may be slightly larger than the composite part to beformed thereon in order to account for a thickness of the facesheet 12and the first insulating material 26. Furthermore, the size of thetooling surface 24 may also take into account an amount of compressionof the first insulating material 26 while under vacuum and autoclavepressure to be applied while curing the composite part.

The first insulating material 26 and the second insulating material 28may be non-conductive material configured for shielding the toolingsurface 24 and/or shielding the impermeable material 32 from heat duringcuring of the composite part. In some embodiments, the first insulatingmaterial 26 and/or the second insulating material 28 may have lowthermal conductivity and may be configured to withstand hightemperatures. For example, the first insulating material 26 and/or thesecond insulating material 28 may b made of fiberglass paper, refractoryinsulation, or other insulating materials. In some embodiments, asubstantially rigid insulating material may be used for the first and/orsecond insulating materials 26,28 and may be configured to resistcompressive force during curing of the composite part. For example,refractory insulation may be rigid and may be troweled onto the toolingsurface 24 and then NC machined to a final contour for the desired shapeof the composite part. However, insulating materials that arecompressible may be used without departing from the scope of thetechnology described herein. In some embodiments, the first and/orsecond insulating materials 26,28 may be made of a material with lowpermeability or material that is substantially impermeable in order toprevent heat transfer therethrough. However, other insulating materialsmay be used without departing from the scope of the invention. The useof vacuum under the impermeable bag may substantially increase thethermal shielding capability of both the first and second insulatingmaterials 26,28.

In some embodiments, the second insulating material 28 may have cuts 40formed therein, such as using water jet cutting or any cutting methodsknown in the art. Specifically, the second insulating material 28 can bean insulating sheet cut to allow at least one of the substructures 36 toprotrude therethrough, as depicted in FIG. 6. The cuts 40 may bepositioned such that the second insulating material 28 serves as atemplate for locating the substructures 36 at a predetermined locationon the skin 34 of the composite part, as later described herein.Additionally or alternatively, the second insulating material 28 mayinclude a plurality of discontinuous insulation panels sized inaccordance with desired spacing between respective substructures orother features of the composite part. For example, the discontinuousinsulation panels may be laid out in a manner to establish correctpositioning of the substructures along the skin 34. Such positioning maybe maintained until consolidation is complete and/or until thecomponents of the substructure are fused to the skin 34. The secondinsulating material 28 may also be engineered, sized, configured, andpositioned such that no portion of the impermeable membrane 32 touches asurface that is heated above the melting temperature of the impermeablemembrane 32.

The source of heat or electricity 30 may be physically and electricallycoupled to the facesheet 12 and may generate sufficient heat to cure,melt, and/or fuse the composite part. Specifically, the source of heator electricity 30 may be a source of joule heat. For example, a sourceof joule heat may include a single turn transformer 42, one or moreconductive wires 44, and at least two bus bars 46,48. The two bus bars46,48 may be configured for placement at opposing ends of the facesheet12 and the conductive wires 44 electrically coupled to the bus bars46,48 may provide joule heating to the facesheet 12. In someembodiments, the conductive wires 46,48 extend from one of the bus bars46 to another one of the bus bars 48 and are threaded through an air gap50 of the single turn transformer 42, as depicted in FIGS. 5a and 5b .The single turn transformer 42 can be connected to an externalelectrical source by at least one source-coupling wire 52 and can beturned on to induce current into the conductive wires 44. Specifically,the single turn transformer 42 may be configured for transforming highvoltage to low voltage and thus high current after penetrating the wallsof a pressure vessel. For example, the single turn transformer 42 may beconfigured to receive 480 VAC from the external electrical source withonly 85 amps and then induce a 4.8 VAC at 8500 amps into thirty-two 4/0copper wires connected to the bus bars 46,48. However, other values andother methods of joule heating or heating of the facesheet 12 may beused without departing from the scope of the technology herein.

The impermeable membrane 32 illustrated in FIGS. 5a and 6 is a flexiblematerial that is substantially or completely impermeable to theatmosphere and/or other gases that may be used for compressive force.For example, the impermeable membrane 32 may be substantiallyimpermeable to atmosphere at a pressure differential of 15 psi or insome embodiments may be impermeable to atmosphere at a pressuredifferential of up to 100 psi. The impermeable membrane 32 may be alow-temperature bag or plastic that may melt at composite cure,composite melt, and/or composite fusing temperatures but is cheaper andmore flexible than higher temperature bags or plastics that aregenerally stiffer. For example, the impermeable membrane 32 may be madeof nylon and have a maximum service temperature in a range ofapproximately 400 degrees F. and/or a melting point in a range ofapproximately 428 to 509 degrees F. However, other flexible impermeablemembranes may be used without departing from the scope of the invention.Furthermore, the impermeable membrane 32 may include pleats 54 to allowfor different features of the composite part, such as substructures 36like frames or stringers extending outward from the composite skin 34.

The impermeable membrane 32 may be configured for placement over thesecond insulating material 28 and the composite part, as later describedherein. The impermeable membrane 32 may also be configured to be sealedto the tooling surface 24 for applying consolidation pressure to thecomposite part when a pressure differential is applied across theimpermeable membrane 32. The impermeable membrane 32 may be sealed tothe tooling surface using sealant tape, mud, or any sealant known in theart. The consolidation pressure may force the impermeable membranetoward the tooling surface 24 under vacuum or autoclave pressure, suchas via an autoclave 56 as depicted in FIG. 5a .

At least a portion of the steps of a method 700 for manufacturingthermoplastic composite parts using the system 10 in accordance withvarious embodiments of the present invention is listed in FIG. 7. Thesteps may be performed in the order as shown in FIG. 7, or they may beperformed in a different order. Further, some steps may be performedconcurrently as opposed to sequentially. In addition, some steps may beomitted. Still further, embodiments of the present invention may beperformed using systems other than system 10 without departing from thescope of the technology described herein.

In some embodiments of the invention, the method 700 may include a stepof placing or forming the skin 34 onto the facesheet 12, as depicted inblock 702. For example, this step may include using the ATL machine 14for laying multiple layers of the composite tape 16 (e.g., each formedfrom courses of composite material) onto the facesheet 12, with thefacesheet 12 laying on the substantially flat surface 18. As describedabove, the facesheet 12 is made of a flexible conductive material. Thisstep may further include tacking welds or applying the magnets 22 ontoat least a portion of the plurality of courses of composite tape 16during ATL, such as down a centerline thereof. For example, permanenttack welds may be applied to the layers of the composite tape 16 viaultrasonic, conduction or other means of melting the composite tape 16together down the centerline or elsewhere. In some embodiments, such asthose using the method 700 for forming half cylindrical parts, acenterline of the part may be the only location where permanent tackwelds are applied, allowing for a desired amount of slippage betweenlayers thereof when the composite material is moved from a flat to acurved surface for curing as described herein.

Additionally or alternatively, the magnets 22 are likewise used totemporarily hold the composite tape 16 in place against the facesheet12, such as between layers of tape layup. This temporary magnetictacking can be used anywhere on the composite tape 16, including but notlimited to the center line thereof. Then, just ahead of the ATL machine14 the magnets 22 may be removed at a point in time between applicationsof each layer of the composite tape 16. Specifically, the magnetplacement apparatus 20 may deploy and remove the magnets 22 usingdifferential magnetic polarity. For example, the magnet placementapparatus 20 may switch between a first polarity and a second polarityfor depositing and picking up the magnets 22 from the compositematerial.

In some embodiments, as depicted in FIGS. 1 and 2, the magnet placementapparatus 20 may be attached to or work in conjunction with the ATLmachine 14 such that a portion of the magnet placement apparatus 20slightly ahead of the ATL machine's tape-laying head is configured toattract and thus pick up magnets 22 from a previous layer of compositetape 16 while a portion of the magnet placement apparatus 20 slightlybehind the ATL machine's tape-laying head is configured to repel andthus deposit magnets 22 onto the freshly laid layer of composite tape16. Alternatively, as described above, the magnet placement apparatus 20may be a rotatable steel ring that moves the magnets from in front ofthe ATL machine's tape-laying head to behind the tape-laying head, wherethe magnets 22 are replaced on a next layer of the composite tape 16.

Furthermore, after all layers of composite tape 16 are laid via the ATLmachine 14, one or more of the magnets 22 may remain on a top layer ofthe composite tape 16 to help maintain composite tape orientation as thefacesheet 12 and composite skin 34 is moved from the flat surface 18 tothe tooling surface 24, as later described herein. For example, a centerline of magnets 22 may remain during this transfer, such that someslippage of composite tape 16 is allowed as the skin 34 is curved tomate with the tooling surface's curvature, but without allowing thecomposite tape's orientation to be negatively affected. Thus, use ofmagnets (or other temporary and permanent tacking methods known in theart) to hold the composite tape 16 in place temporarily prior to cure isadvantageous over welding or other permanent tacking methods in areaswhere some material slippage allows for easier transfer of the compositematerial from the flat surface 18 to the curved tooling surface 24without undesirable buckling, puckers, or wrinkles of the composite tape16.

The method 700 may further include a step of transferring the facesheet12 with the skin thereon onto the tooling surface 24, as depicted inblock 704. Specifically, this step may include transferring thefacesheet 12 with the skin 34 thereon from the flat surface 18 to thetooling surface 24, and the tooling surface 24 may be curved such thatthe facesheet 12 with the skin 34 thereon is curved by the toolingsurface 24. This method of laying up composite material in the flat andthen transferring it to a curved tooling surface advantageously allowsATL methods of composite layup to be used for a curved composite part,saving time and money over AFP methods traditionally used for curvedcomposite parts.

The transferring step may be performed manually or may be performed bycrane, magnetic lifters, and/or spreader bars. However, any transferringmethod may be used without departing from the scope of the technologydescribed herein. Furthermore, this transferring step may furthercomprise bending or otherwise conforming the facesheet 12 elasticallywith edges of the facesheet 12 clamped or otherwise dogged down to thetooling surface 24, buckling the facesheet 12 into the simple contour ofthe tooling surface 24. Additionally or alternatively, weight of theskin 34 and/or other components placed thereon may press the facesheet12 against the tooling surface 24. However, in some embodiments, it maynot be necessary that the facesheet 12 be completely intimate with thefirst insulating material 26 at this transferring step since finalvacuum bag and pressure differential across the impermeable materialwill force the facesheet 12 against the first insulation layer in latersteps described herein.

As noted above, the tooling surface 24 used in this step 704 may be madeof insulating material and/or the first insulating material 26 may bepositioned between the tooling surface 24 and the facesheet 12.Specifically, the first insulating material 26 may be placed onto thetooling surface 24 prior to placement of the facesheet 12 thereon. Insome embodiments of the invention, in addition to or as an alternativeto the magnets 22 described above, a temporary bag (not shown)comprising any impermeable material or vacuum bag may be applied overthe composite skin 34, sealed to the facesheet 12, and vacuumed towardthe facesheet 12 to hold the composite skin 34 in place during thistransfer of the facesheet 12 and composite skin 34 to the toolingsurface 24. However, pressure applied may be less than pressure appliedto the impermeable membrane 32 during composite material cure, such thatsome material slippage and flexing is allowed as the layers of compositetape 16 are curved by the curvature of the tooling surface 24. Thetemporary bag may be removed once the facesheet 12 and the skin 34 aretransferred to the tooling surface 24.

The method 700 may further include a step of electrically and/orphysically contacting the facesheet 12 with the source of heat orelectricity 30, as depicted in block 706. In some embodiments, the twobus bars 46,48 are electrically coupled to the conductive wires 44 andare clamped directly to the facesheet 12 at opposing ends of thefacesheet 12. However, in other embodiments of the invention, portionsof the facesheet 12 at or near opposing edges thereof are forced againstthe bus bars 46,48 during vacuum or autoclave pressure compressing theimpermeable membrane 32 toward the tooling surface 24. In someembodiments, the bus bars 46,48 may comprise more than two bus bars orany other electrical coupling configuration without departing from thescope of the technology described herein. This step may further comprisethreading the conductive wires 44 from one of the bus bars 46, throughan air gap 50 of the single turn transformer 42, and to the other of thebus bars 48.

Next, in some embodiments, the method 700 may include a step of placingat least one substructure 36 onto the skin 34, as depicted in block 708,and placing the second insulating material 28 over the skin 34 and/orportions of the substructure 36, as depicted in lock 710. As notedabove, the substructure 36 may be other composite components forattachment to the composite skin 34, such as frames and stringers for aninner mold line (IML) of an aircraft component. The substructure 36 maybe pre-cured and placed onto the skin 34 for fusing thereto during cureof the skin 34. Furthermore, the substructure 36 may be tacked in placeon the skin 34 to temporarily hold the substructure 36 in place prior tocuring of the skin 34 and fusing of the substructure 36 thereto.

The second insulating material 28 may be an insulating sheet cut toallow the substructure 36 or substructures to protrude therethrough. Thesecond insulating material 28 may further be used as a template forlocating the substructure 36 or substructures at predetermined locationson the skin 34. For example, in some embodiments, the placement of thesubstructures 36 and the second insulating material 28 may be performedsubstantially simultaneously or in conjunction with each other toprovide proper placement of substructures 36 like frames and stringersrelative to the skin 34 while also covering the skin 34 with insulationso that the impermeable membrane 32 and most of the substructure 36beyond the faying surface thereof is protected from heat coming from thefacesheet 12. Thus, during cure, remelting, and/or fusing of thecomposite part, only the skin 34 and faying surfaces of thesubstructures 36 are exposed to full curing heat. This allows someportions of the substructures 36 to maintain their previously curedshapes and configurations, while still allowing the substructures 36 tofuse to the skin 34.

The method 700 may further include a step of placing the impermeablemembrane 32 over the second insulating material 28, the substructure 36,and/or the skin 34, as depicted in block 712, and sealing theimpermeable membrane 32 to the tooling surface 24, as depicted in block714. Specifically, the impermeable membrane 32 may extend to portions ofthe tooling surface 24 that extend further outward than the secondinsulating material 28, as depicted in FIG. 5a . Likewise, the secondinsulating material 28 may be configured to extend further outward thanthe facesheet 12, such that the impermeable membrane 32 is protectedfrom facesheet heat, as noted above. Any type of sealant tape, mud, orapparatus may be used to seal the impermeable membrane 32 to the toolingsurface 24 without departing from the scope of the technology describedherein.

Then the method 700 may include a step of compressing the skin 34 viaapplying a pressure differential that forces the impermeable membrane 32toward the tooling surface 24, as depicted in block 716, then heatingthe facesheet 12 to a cure temperature, melting temperature, and/orfusing temperature via the source of heat or electricity 30 as depictedin block 718. In some embodiments, a vacuum port formed into and throughthe impermeable membrane 32 may be used to evacuate air or gas out frombetween the impermeable membrane 32 and the tooling surface 24 tocompress the impermeable membrane 32 toward the tooling surface 24,thereby compressing the skin 34 and/or portions of the substructures 36.Additionally or alternatively, the tooling surface 24, first insulatingmaterial 36, skin 34, substructures 36, second insulating material 28,impermeable membrane 32, and at least portions of the source of heat orelectricity 30 may be placed inside the autoclave 56 to therebyproviding autoclave pressure to compress the impermeable membrane 32.For example, the impermeable membrane 32 may provide more than 15 PSIand up to approximately 215 PSI of pressure to the skin 34 of thecomposite part.

Note that the autoclave 56 is a cool autoclave, remaining well belowcure, melting, or fusing temperatures throughout heating of thecomposite part or fusing of substructures to the composite part. Forexample, the autoclave 56 may remain at a temperature less than100-degrees Fahrenheit, or less than 90-degrees Fahrenheit. Morespecifically, in one embodiment the autoclave 56 may remain at atemperature of approximately 85-degrees Fahrenheit throughout compositepart cure using the methods herein. Additionally or alternatively, theautoclave 56 may remain well below melting temperatures and/or fusingtemperatures of the composite part. This advantageously allows the useof low-temp vacuum bags or impermeable membranes with low temperaturemelting points and further saves on the amount of energy consumed toheat and/or cure the composite skin 34, since only the facesheet 12, theskin 34, and faying surfaces of the substructure 36 require heating.Furthermore, the tooling surface 24 does not suffer from thermalexpansion since it is not heated, thus allowing for more accurate sizingof the resulting composite part.

In some embodiments, the tooling surface may even be actively cooledand/or fans may be added to assist in maintaining a uniform temperaturein the autoclave 56 and preventing the tooling surface 24 from gettingtoo hot and expanding an undesirable amount. Additionally, since onlythe faying surface of the substructures 36 are heated in this method700, multiple complex tooling or mold components to provide sufficientpressure for maintaining shape and consolidation of thepreviously-formed substructures 36 are not needed, as they are notmelted again during curing of the skin 34 due to the second insulatingmaterial 28.

Heating the facesheet 12 to the cure temperature, the meltingtemperature, and/or the fusing temperature may comprise applying jouleheat via electric current through the facesheet 12. For example, thesingle turn transformer 42 may be turned on to receive electrical powerfrom an external source and then transform the voltage output induced onthe conductive wires 44, thereby increasing the amperage provided to thefacesheet 12 through the conductive wires 44 and the bus bars 46,48. Asdescribed above, with the conductive wires 44 extending through the airgap 50, current is induced into the one or more conductive wires 44 whenthe single turn transformer 42 is turned on. This configurationadvantageously allows large wires needed for providing high enoughcurrent for joule heating the skin 34 to cure temperature, meltingtemperature, or fusing temperature while requiring only a small openingin the autoclave 56 for receiving external electrical power (e.g., viathe at least one source-coupling wire 52), thus making it easier andless expensive to maintain autoclave pressure during cure cycles usingthe method described herein.

Finally, the method 700 may include a step of cooling the facesheet 12and skin 34, as depicted in block 720. In some embodiments, this stepmay be required after the composite part has hardened. Alternatively, inother embodiments, this cooling may be required to harden the skin 34into the composite part. Once the skin 34, the substructure 36, or anyother heated components of the present invention are cooled, theimpermeable membrane 32 may be removed and the resulting composite partmay be removed from the tooling surface 24 and the facesheet 12.

In some embodiments, alternatives may be used for one or more of thesteps of method 700. For example, the tooling surface 24 and the sourceof heat or electricity 30 could be replaced with the heating elementsand the exemplary tool or the platform described in U.S. patentapplication Ser. No. 16/404,794, filed on May 7, 2019 (hereinafter the'794 application), incorporated by reference herein in its entirety.Such alternatives are also described in PCT Application No.PCT/US20/31784, filed on May 7, 2020, which is likewise incorporated byreference herein in its entirety.

Specifically, such an alternative may still include performing the stepsdescribed herein of ATL composite tape layup on a flat surface, but thenmay include alternatively transferring the faceplate 12 and the skin 34to a curved-surface tool such as the exemplary tool in the '794application, and then heating the skin 34 and the substructures 36 usingthe heating elements of the '794 application. This alternativeembodiment may optionally also be performed without the first insulatinglayer 26 described herein. In some examples of this alternativeembodiment, the facesheet 12 may be a breather or some other materialthat allows heat to flow therethrough to the skin 34, with or withoutbeing conductive. Other alternatives known in the art of compositematerial manufacture or aircraft component manufacturing may be used inplace of various steps described herein without departing from the scopeof the invention.

The present invention has been described in relation to particularexamples, which are intended in all respects to be illustrative ratherthan restrictive. From the foregoing, it will be seen that thisinvention is one well adapted to attain all the ends and objects setforth above, together with other advantages which are obvious andinherent to the system and method. It will be understood that certainfeatures and subcombinations are of utility and may be employed withoutreference to other features and subcombinations. This is contemplated byand is within the scope of the claims.

Some aspects of this disclosure have been described with respect to theexamples provided in the figures. Additional aspects of the disclosurewill now be described that may be related subject matter included in oneor more claims or clauses of this application at the time of filing, orone or more related applications, but the claims or clauses are notlimited to only the subject matter described in the below portions ofthis description. These additional aspects may include featuresillustrated by the figures, features not illustrated by the figures, andany combination thereof. When describing these additional aspects,reference may be made to elements depicted by the figures forillustrative purposes.

As used herein and in connection with the claims listed hereinafter, theterminology “any of clauses” or similar variations of said terminologyis intended to be interpreted such that features of claims/clauses maybe combined in any combination. For example, an exemplary clause 4 mayindicate the method/apparatus of any of clauses 1 through 3, which isintended to be interpreted such that features of clause 1 and clause 4may be combined, elements of clause 2 and clause 4 may be combined,elements of clause 3 and 4 may be combined, elements of clauses 1, 2,and 4 may be combined, elements of clauses 2, 3, and 4 may be combined,elements of clauses 1, 2, 3, and 4 may be combined, and/or othervariations.

The following clauses are aspects contemplated herein.

1. A method for manufacturing composite parts, the method comprising thesteps of: placing a skin made of uncured composite material onto afacesheet lying flat on a flat surface; transferring the facesheet withthe skin thereon onto a curved tooling surface; conforming the facesheetwith the skin thereon to the curved tooling surface; and heating theskin to a cure temperature, a melting temperature, or a fusingtemperature of the skin while the skin and the facesheet are conformedto the curved tooling surface.

2. The method of clause 1, wherein placing or forming the skin furthercomprises applying a plurality of courses of composite tape onto thefacesheet using an automated tape layup (ATL) method while the facesheetis laid flat on a flat surface.

3. The method of clauses 1 or 2, further comprising compressing the skinduring heating of the skin, wherein compressing the skin is performed byvacuum sealing an impermeable membrane toward the tooling surface andapplying autoclave pressure within a cool autoclave, wherein the coolautoclave applies autoclave pressure at temperatures below the a curetemperature, a melting temperature, or a fusing temperature of the skin.

4. The method of any one of clauses 1-3, wherein the facesheet is madeof a conductive material.

5. The method of any one of clauses 1-4, wherein the curved toolingsurface is made of insulating material or a first insulating material ispositioned between the tooling surface and the facesheet.

6. The method of any one of clauses 1-5, further comprising at least oneof electrically and physically contacting the facesheet with a source ofheat or electricity.

7. The method of clause 6, wherein the source of heat or electricityincludes two bus bars at opposing ends of the facesheet and one or moreconductive wires providing joule heating to the face sheet, wherein theone or more conductive wires extend from one of the bus bars to theother of the bus bars and are threaded through an air gap of a singleturn transformer, such that heating the facesheet includes inducingcurrent into the one or more conductive wires with the single turntransformer.

8. The method of any one of clauses 1-7, further comprising placing atleast one substructure onto the skin prior to heating the skin.

9. The method of any one of clauses 1-8, further comprising placing asecond insulating material over the skin, wherein the second insulatingmaterial is an insulating sheet cut to allow the at least onesubstructure to protrude therethrough, such that the second insulatingmaterial serves as a template for locating the substructure at apredetermined location on the skin.

10. The method of any one of clauses 1-9, further comprising compressingthe skin during heating of the skin, wherein compressing the skin isperformed by vacuum sealing an impermeable membrane toward the toolingsurface and applying autoclave pressure within a cool autoclave, whereinthe cool autoclave applies autoclave pressure at temperatures below thecure temperature, the melting temperature, or fusing temperature of theskin.

11. A method for manufacturing composite parts, the method comprisingthe steps of: forming a skin by placing a plurality of courses ofcomposite tape onto a facesheet using an automated tape layup (ATL)method while the facesheet is laid flat on a flat surface; transferringthe facesheet with the skin thereon from the flat surface to a toolingsurface, wherein the tooling surface is curved and the facesheet withthe skin thereon is curved by the tooling surface; compressing the skinvia applying a pressure differential; heating the facesheet to a curetemperature, a melting temperature, or fusing temperature of the skinvia a source of heat or electricity thereby heating the skin thereon.

12. The method of clause 11, wherein the facesheet is a flexibleconductive sheet of material and wherein the tooling surface is made ofinsulating material or a first insulating material is positioned betweenthe tooling surface and the facesheet such that the source of heat orelectricity provides joule heat to the facesheet during the step ofheating the facesheet.

13. The method of clause 11 or 12, placing at least one substructureonto the skin, wherein the substructure is made of composite material;and placing a second insulating material over the skin, wherein thesecond insulating material is an insulating sheet cut to allow the atleast one substructure to protrude therethrough, such that the secondinsulating material serves as a template for locating the substructureat a predetermined location on the skin.

14. The method of any one of clauses 11-13, wherein the source of heator electricity includes at least two bus bars at opposing ends of thefacesheet and one or more conductive wires providing joule heating tothe facesheet, wherein the facesheet is made of conductive material.

15. The method of clause 14, wherein the one or more conductive wiresextend from one of the bus bars to the other of the bus bars and arethreaded through an air gap of a single turn transformer, such thatheating the facesheet includes inducing current into the one or moreconductive wires with the single turn transformer.

16. The method of any one of clauses 11-15, wherein compressing the skinis performed by vacuum sealing an impermeable membrane toward thetooling surface and applying autoclave pressure within a cool autoclave,wherein the cool autoclave applies autoclave pressure at temperaturesbelow the cure temperature, the melting temperature, or the fusingtemperature of the skin.

17. The method of any one of clauses 11-16, further comprising applyingmagnets onto at least a portion of the plurality of courses of compositetape during ATL, thereby temporarily holding the plurality of courses ofcomposite tape in place against the facesheet, and removing the magnetsat a point in time between application of each layer of the plurality ofcourses of composite tape during ATL, wherein the facesheet isconductive.

18. A method for manufacturing thermoplastic composite parts, the methodcomprising the steps of forming a skin by placing a plurality of coursesof composite tape onto a facesheet using an automated tape layup (ATL)method while the facesheet is laid flat on a flat surface, wherein thefacesheet is a conductive sheet of material; transferring the facesheetwith the skin thereon from the flat surface to a tooling surface,wherein the tooling surface has a simple curvature and the facesheetwith the skin thereon is curved by the tooling surface, wherein thetooling surface is made of insulating material or a first insulatingmaterial is positioned between the tooling surface and the facesheet;electrically and/or physically contacting the facesheet with a source ofjoule heat; placing a plurality of substructures onto the skin, whereinthe substructures include at least one of composite frames and compositestringers; placing a second insulating material over the skin; placingan impermeable membrane over the second insulating material, thesubstructure, and the skin; sealing the impermeable membrane to thetooling surface; placing the tooling surface, the skin, the plurality ofsubstructures, the facesheet, the first insulating material, the secondinsulating material, the impermeable membrane, and the joule heatingsource into a cool autoclave, wherein the cool autoclave appliesautoclave pressure at temperatures below a cure temperature, a meltingtemperature, or a fusing temperature of the skin; compressing the skinvia applying a pressure differential that forces the impermeablemembrane toward the tooling surface using at least one of vacuum andautoclave pressure from the cooling autoclave; and heating the facesheetto the cure temperature, the melting temperature, or the fusingtemperature of the skin via the source of joule heat, wherein the sourceof joule heat is a single turn transformer, wherein a plurality ofconductive wires extending from one end of the skin to an opposite endof the skin are threaded through an air gap of the single turntransformer, such that heating the facesheet includes inducing currentinto the plurality of conductive wires with the single turn transformer.

19. The method of clause 18, wherein the second insulating material isan insulating sheet cut to allow the plurality of substructures toprotrude therethrough, such that the second insulating material servesas a template for locating the plurality of substructures atpredetermined locations relative to each other on the skin.

20. The method of clause 18 or 19, further comprising applying magnetsonto at least a portion of the plurality of courses of composite tapeduring ATL, thereby temporarily holding the plurality of courses ofcomposite tape in place against the facesheet, and removing the magnetsat a point in time between application of each layer of the plurality ofcourses of composite tape during ATL.

21. A system for forming and curing a composite part, the systemcomprising: a facesheet made of a conductive material for placement ofthe composite part thereon; a tooling surface, wherein the toolingsurface is made of insulating material or a first insulating material ispositioned onto the tooling surface, wherein the facesheet is positionedon at least one of the tooling surface and the first insulatingmaterial, wherein at least a portion of the tooling surface is not flat;and a source of heat or electricity at least one of physically andelectrically coupled to the facesheet, wherein the source of heat orelectricity generates sufficient heat to cure, melt, or fuse thecomposite part.

22. The system of clause 21, further comprising an impermeable membranefor placement over the composite part, wherein the impermeable membraneis sealed to the tooling surface and applies consolidation pressure tothe composite part when a pressure differential is applied to theimpermeable membrane forcing the impermeable membrane toward the toolingsurface.

23. The system of clause 21 or 22, wherein the tooling surface is curvedand the facesheet is curved by the tooling surface.

24. The system any one of clauses 21-23, further comprising a secondinsulating material for placement over the composite part, wherein thesecond insulating material is an insulating sheet cut to allow at leastone substructure of the composite part to protrude therethrough, suchthat the second insulating material serves as a template for locatingthe substructure at a predetermined location on a skin of the compositepart.

25. The system of any one of clauses 21-24, wherein the source of heator electricity includes two bus bars at opposing ends of the facesheetand one or more conductive wires providing joule heating to the facesheet.

26. The system of clause 25, wherein the source of heat or electricityfurther comprises a single turn transformer, wherein the one or moreconductive wires extend from one of the bus bars to another one of thebus bars and are threaded through an air gap of the single turntransformer such that heating the facesheet includes inducing currentinto the one or more conductive wires with the single turn transformer.

27. The system of any one of clauses 21-26, wherein the facesheet ismade of steel.

28. The system of any one of clauses 21-27, further comprising anautomated tape layup (ATL) machine for laying courses of compositematerial onto the facesheet on a flat surface prior to insertion of thefacesheet onto the tooling surface.

29. The system of clause 28, further comprising a magnet-placementapparatus operable to lay down and pick up magnets by effectuating achange in polarity, wherein the magnet-placement apparatus is configuredto place magnets onto a first layer of courses of composite materialduring layup by the ATL machine and to pick up magnets from the coursesof composite material prior to the ATL machine placing a second layer ofcourses of composite material.

30. A system for forming and curing a composite part, the systemcomprising: a facesheet made of a conductive sheet of material forplacement of the composite part thereon; a tooling surface, wherein thetooling surface is made of insulating material or a first insulatingmaterial is positioned onto the tooling surface, wherein the facesheetis positioned on at least one of the tooling surface and the firstinsulating material, wherein the tooling surface has a simple curvature;a second insulating material for placement over the composite part; anda source of joule heat at least one of physically and electricallycoupled to the facesheet, wherein the source of joule heat generatessufficient heat to cure, melt, or fuse the composite part.

31. The system of clause 30, further comprising an impermeable membranefor placement over the second insulating material and the compositepart, wherein the impermeable membrane is sealed to the tooling surfaceand applies consolidation pressure to the composite part when a pressuredifferential is applied to the impermeable membrane forcing theimpermeable membrane toward the tooling surface.

32. The system of clause 30 or 31, wherein the second insulatingmaterial is an insulating sheet cut to allow at least one substructureof the composite part to protrude therethrough, such that the secondinsulating material serves as a template for locating the substructureat a predetermined location on a skin of the composite part.

33. The system of any one of clauses 30-32, wherein the source of jouleheat includes a single turn transformer, two bus bars made of copper atopposing ends of the facesheet, and one or more conductive wires,wherein the one or more conductive wires extend from one of the bus barsto another one of the bus bars and are threaded through an air gap ofthe single turn transformer such that heating the facesheet includesinducing current into the one or more conductive wires with the singleturn transformer.

34. The system of any one of clauses 30-33, further comprising anautomated tape layup (ATL) machine for laying courses of compositematerial onto the facesheet on a flat surface prior to insertion of thefacesheet onto the tooling surface.

35. The system of clause 34, further comprising a magnet-placementapparatus operable to lay down and pick up magnets by effectuating achange in polarity, wherein the magnet-placement apparatus is configuredto place magnets onto a first layer of courses of composite materialduring layup by the ATL machine and to pick up magnets from the coursesof composite material prior to the ATL machine placing a second layer ofcourses of composite material.

36. A system for forming and curing a thermoplastic composite part, thesystem comprising: a facesheet made of a conductive sheet of materialfor placement of the thermoplastic composite part thereon; a toolingsurface, wherein the tooling surface is made of insulating material or afirst insulating material is positioned onto the tooling surface,wherein the facesheet is positioned on at least one of the toolingsurface and the first insulating material, wherein the tooling surfacehas a simple curvature; a second insulating material for placement overthe thermoplastic composite part; an impermeable membrane placed overthe second insulating material and the thermoplastic composite part,wherein the impermeable membrane is sealed to the tooling surface and isconfigured to apply consolidation pressure to the thermoplasticcomposite part when a pressure differential is applied to theimpermeable membrane forcing the impermeable membrane toward the toolingsurface; and a source of joule heat at least one of physically andelectrically coupled to the facesheet, wherein the source of joule heatgenerates sufficient heat to cure, melt, or fuse the thermoplasticcomposite part, wherein the source of joule heat includes at least twoconductive bus bars attached to opposing ends of the facesheet, and oneor more conductive wires providing current to heat the facesheet.

37. The system of clause 36, wherein the second insulating material isan insulating sheet cut to allow a plurality of frames and stringers ofthe thermoplastic composite part to protrude therethrough, such that thesecond insulating material serves as a template for locating the framesand stringers at a predetermined location on a skin of the thermoplasticcomposite part.

38. The system of clause 36 or 37, wherein the source of joule heatfurther includes a single turn transformer, wherein the at least two busbars are made of copper, wherein the one or more conductive wires extendfrom one of the bus bars to another one of the bus bars and are threadedthrough an air gap of the single turn transformer such that heating thefacesheet includes inducing current into the one or more conductivewires with the single turn transformer.

39. The system of any one of clauses 36-38, further comprising anautomated tape layup (ATL) machine for laying courses of compositematerial onto the facesheet on a flat surface prior to insertion of thefacesheet onto the tooling surface.

40. The system of clause 39, further comprising a magnet-placementapparatus operable to lay down and pick up magnets by effectuating achange in polarity, wherein the magnet-placement apparatus is configuredto place magnets onto a first layer of courses of composite materialduring layup by the ATL machine and to pick up magnets from the coursesof composite material prior to the ATL machine placing a second layer ofcourses of composite material.

The following claims are presented with single dependencies to complywith U.S. practice. However, unless the features of the claims areincompatible, it is envisaged that any claim may be dependent upon anyone, or any combination, of the preceding claims.

1. A method for manufacturing composite parts, the method comprising thesteps of: placing a skin made of uncured or unfused composite materiallayers onto a facesheet lying on a flat surface; transferring thefacesheet with the skin thereon onto a curved tooling surface;conforming the facesheet with the skin thereon to the curved toolingsurface; and heating the skin to a cure temperature, a meltingtemperature, or a fusing temperature of the skin while the skin and thefacesheet are conformed to the curved tooling surface.
 2. The method ofclaim 1, wherein placing the skin further comprises applying a pluralityof courses of composite tape onto the facesheet using an automated tapelayup (ATL) method while the facesheet is laid flat on the flat surface.3. The method of claim 1, further comprising compressing the skin duringheating of the skin, wherein compressing the skin is performed by vacuumsealing an impermeable membrane toward the tooling surface and applyingautoclave pressure within a cool autoclave, wherein the cool autoclaveapplies autoclave pressure at temperatures below the a cure temperature,a melting temperature, or a fusing temperature of the skin.
 4. Themethod of claim 1, wherein the facesheet is made of a conductivematerial.
 5. The method of claim 4, wherein the curved tooling surfaceis made of insulating material or a first insulating material ispositioned between the tooling surface and the facesheet.
 6. The methodof claim 4, further comprising at least one of electrically andphysically contacting the facesheet with a source of heat orelectricity.
 7. The method of claim 6, wherein the source of heat orelectricity includes two bus bars at opposing ends of the facesheet andone or more conductive wires providing joule heating to the face sheet,wherein the one or more conductive wires extend from one of the bus barsto the other of the bus bars and are threaded through an air gap of asingle turn transformer, such that heating the facesheet includesinducing current into the one or more conductive wires with the singleturn transformer.
 8. The method of claim 1, further comprising placingat least one substructure onto the skin prior to heating the skin. 9.The method of claim 8, further comprising placing a second insulatingmaterial over the skin, wherein the second insulating material is aninsulating sheet cut to allow the at least one substructure to protrudetherethrough, such that the second insulating material serves as atemplate for locating the substructure at a predetermined location onthe skin.
 10. The method of claim 1, further comprising compressing theskin during heating of the skin, wherein compressing the skin isperformed by vacuum sealing an impermeable membrane toward the toolingsurface and applying autoclave pressure within a cool autoclave, whereinthe cool autoclave applies autoclave pressure at temperatures below thecure temperature, the melting temperature, or fusing temperature of theskin.
 11. A method for manufacturing composite parts, the methodcomprising the steps of: forming a skin by placing a plurality ofcourses of composite tape onto a facesheet using an automated tape layup(ATL) method while the facesheet is laid flat on a flat surface;transferring the facesheet with the skin thereon from the flat surfaceto a tooling surface, wherein the tooling surface is curved and thefacesheet with the skin thereon is curved by the tooling surface;compressing the skin via application of a pressure differential; andheating the facesheet to a cure temperature, a melting temperature, orfusing temperature of the skin via a source of heat or electricity,thereby heating the skin thereon.
 12. The method of claim 11, whereinthe facesheet is a flexible conductive sheet of material and wherein thetooling surface is made of insulating material or a first insulatingmaterial is positioned between the tooling surface and the facesheetsuch that the source of heat or electricity provides joule heat to thefacesheet during the step of heating the facesheet.
 13. The method ofclaim 11, further comprising the steps of: placing at least onesubstructure onto the skin, wherein the substructure is made ofcomposite material; and placing a second insulating material over theskin, wherein the second insulating material is an insulating sheet cutto allow the at least one substructure to protrude therethrough, suchthat the second insulating material serves as a template for locatingthe substructure at a predetermined location on the skin.
 14. The methodof claim 11, wherein the source of heat or electricity includes at leasttwo bus bars at opposing ends of the facesheet and one or moreconductive wires providing joule heating to the facesheet, wherein thefacesheet is made of conductive material.
 15. The method of claim 14,wherein the one or more conductive wires extend from one of the bus barsto the other of the bus bars and are threaded through an air gap of asingle turn transformer, such that heating the facesheet includesinducing current into the one or more conductive wires with the singleturn transformer.
 16. The method of claim 11, wherein compressing theskin is performed by vacuum sealing an impermeable membrane toward thetooling surface and applying autoclave pressure within a cool autoclave,wherein the cool autoclave applies autoclave pressure at temperaturesbelow the cure temperature, the melting temperature, or the fusingtemperature of the skin.
 17. The method of claim 11, further comprisingapplying magnets onto at least a portion of the plurality of courses ofcomposite tape during the ATL, thereby temporarily holding the pluralityof courses of composite tape in place against the facesheet, andremoving the magnets at a point in time between application of eachlayer of the plurality of courses of composite tape during the ATL,wherein the facesheet is conductive.
 18. A method for manufacturingthermoplastic composite parts, the method comprising the steps of:forming a skin by placing a plurality of courses of composite tape ontoa facesheet using an automated tape layup (ATL) method while thefacesheet is laid flat on a flat surface, wherein the facesheet is aconductive sheet of material; transferring the facesheet with the skinthereon from the flat surface to a tooling surface, wherein the toolingsurface has a simple curvature and the facesheet with the skin thereonis curved by the tooling surface, wherein the tooling surface is made ofinsulating material or a first insulating material is positioned betweenthe tooling surface and the facesheet; electrically and/or physicallycontacting the facesheet with a source of joule heat; placing aplurality of substructures onto the skin, wherein the substructuresinclude at least one of composite frames and composite stringers;placing a second insulating material over the skin; placing animpermeable membrane over the second insulating material, thesubstructure, and the skin; sealing the impermeable membrane to thetooling surface; placing the tooling surface, the skin, the plurality ofsubstructures, the facesheet, the first insulating material, the secondinsulating material, the impermeable membrane, and the joule heatingsource into a cool autoclave, wherein the cool autoclave appliesautoclave pressure at temperatures below a cure temperature, a meltingtemperature, or a fusing temperature of the skin; compressing the skinvia applying a pressure differential that forces the impermeablemembrane and the facesheet toward the tooling surface using at least oneof vacuum and autoclave pressure from the cooling autoclave; and heatingthe facesheet to the cure temperature, the melting temperature, or thefusing temperature of the skin via the source of joule heat, wherein thesource of joule heat is a single turn transformer, wherein a pluralityof conductive wires extending from one end of the skin to an oppositeend of the skin are threaded through an air gap of the single turntransformer, such that heating the facesheet includes inducing currentinto the plurality of conductive wires with the single turn transformer.19. The method of claim 18, wherein the second insulating material is aninsulating sheet cut to allow the plurality of substructures to protrudetherethrough, such that the second insulating material serves as atemplate for locating the plurality of substructures at predeterminedlocations relative to each other on the skin.
 20. The method of claim18, further comprising applying magnets onto at least a portion of theplurality of courses of composite tape during the ATL, therebytemporarily holding the plurality of courses of composite tape in placeagainst the facesheet, and removing the magnets at a point in timebetween application of each layer of the plurality of courses ofcomposite tape during the ATL.